Apparatus and method for managing reference frame buffer in layered video coding

Abstract

An apparatus for encoding or decoding an image by storing and managing a reference frame used to encode or decode an encoding target image frame. To encode image frames classified into a plurality of layers, the apparatus may include a layer identification unit identifying a layer that includes a first encoding target frame, a frame storage unit storing at least one storage frame associated with the first encoding target frame, a reference frame selector selecting a reference frame from the at least one storage frame, based on the identified layer, and a frame encoder encoding the first encoding target frame by referring to the selected reference frame, wherein the frame storage unit stores the first encoding target frame as a storage frame associated with a second encoding target frame.

1 . An apparatus for encoding image frames classified into a plurality of layers, the apparatus comprising:
 a frame storage unit to store at least one storage frame associated with a first encoding target frame;   a reference frame selector to select a reference frame from the at least one storage frame, based on an identified layer that includes the first decoding target frame; and   a frame encoder to encode the first encoding target frame by referring to the selected reference frame.   
   
   
       2 . The apparatus of  claim 1 , further comprising:
 a storage decision unit to decide whether to store the first encoding target frame based on the identified layer,   wherein the frame storage unit stores the first encoding target frame as a storage frame associated with a second encoding target frame, depending on the decision.   
   
   
       3 . The apparatus of  claim 2 , wherein when the storage decision unit decides to store the first encoding target frame, the frame storage unit deletes an earliest storage frame, from storage frames that are included in the same layer as, or an upper layer of, the first encoding target frame. 
   
   
       4 . The apparatus of  claim 1 , wherein when the identified layer is a top layer, the storage decision unit decides not to store the first encoding target frame. 
   
   
       5 . The apparatus of  claim 1 , wherein the reference frame selector selects, as the reference frame, a storage frame included in the same layer as the first encoding target frame or a storage frame included in a lower layer of the first encoding target frame. 
   
   
       6 . The apparatus of  claim 5 , further comprising:
 a storage frame sorting unit to sort storage frames according to the layer that includes the storage frame,   wherein the reference frame selector selects the reference frame based on the sorted storage frames.   
   
   
       7 . The apparatus of  claim 1 , wherein the frame encoder generates a prediction image frame with respect to the first encoding target frame based on the reference frame, and encodes a difference between the prediction image frame and the first encoding target frame. 
   
   
       8 . An apparatus for decoding a multi-layered encoded image, the apparatus comprising:
 a frame storage unit to store at least one storage frame associated with a first decoding target frame;   a reference frame selector to select a reference frame from the at least one storage frame based on an identified layer that includes the first decoding target frame; and   a frame decoder to decode the first decoding target frame by referring to the selected reference frame.   
   
   
       9 . The apparatus of  claim 8 , further comprising:
 a storage decision unit to decide whether to store the first decoding target frame based on the identified layer,   wherein the frame storage unit stores the first decoding target frame as a storage frame associated with a second decoding target frame, depending on the decision.   
   
   
       10 . The apparatus of  claim 8 , wherein, when the identified layer is a top layer, the storage decision unit decides not to store the first decoding target frame. 
   
   
       11 . The apparatus of  claim 8 , wherein the reference frame selector selects, as the reference frame, a storage frame included in the same layer as the first decoding target frame or a storage frame included in a lower layer of the first decoding target frame. 
   
   
       12 . The apparatus of  claim 11 , further comprising:
 a storage frame sorting unit to sort storage frames according to the layer that includes the storage frame,   wherein the reference frame selector selects the reference frame based on the sorted storage frames.   
   
   
       13 . A method for decoding a multi-layered encoded image using an image decoding apparatus, the method comprising:
 storing at least one storage frame associated with a first decoding target frame;   selecting a reference frame from the at least one storage frame based on an identified layer that includes the first decoding target frame; and   decoding, by the image decoding apparatus, the first decoding target frame by referring to the selected reference frame.   
   
   
       14 . The method of  claim 13 , further comprising:
 deciding whether to store the first decoding target frame based on the identified layer,   wherein the storing of the first decoding target frame stores the first decoding target frame as a storage frame associated with a second decoding target frame, depending on the deciding.   
   
   
       15 . The method of  claim 13 , wherein, when the identified layer is a top layer, the deciding decides not to store the first decoding target frame. 
   
   
       16 . The method of  claim 13 , wherein the selecting selects, as the reference frame, a storage frame included in the same layer as the first decoding target frame or a storage frame included in a lower layer of the first decoding target frame. 
   
   
       17 . The method of  claim 16 , further comprising:
 sorting the storage frames according to the layer that includes the storage frame,   wherein the selecting selects the reference frame based on the sorted storage frames.   
   
   
       18 . At least one computer-readable recording medium storing computer readable code comprising a program for implementing the method of  claim 13 . 
   
   
       19 . An apparatus for encoding image frames classified into a plurality of layers, the apparatus comprising:
 a layer identification unit to identify a layer that includes an encoding target frame;   a frame storage unit to store at least one storage frame associated with the encoding target frame;   a storage frame sorting unit to sort the at least one storage frame according to a layer that includes the at least one storage frame;   a reference frame selector to select a reference frame from the sorted the at least one storage frame, based on the identified layer; and   a frame encoder to encode the encoding target frame by referring to the selected reference frame.   
   
   
       20 . The apparatus of  claim 19 , wherein the reference frame selector selects, as the reference frame, a frame that is encoded and is stored prior to the encoding target frame, among storage frames included in the same layer as the encoding target frame or storage frames included in a lower layer of the encoding target frame. 
   
   
       21 . An apparatus for decoding a multi-layered encoded image, the apparatus comprising:
 a layer identification unit to identify a layer that includes a decoding target frame;   a frame storage unit to store at least one storage frame associated with the decoding target frame;   a storage frame sorting unit to sort the at least one storage frame according to a layer that includes the at least one storage frame;   a reference frame selector to select a reference frame from the sorted at least one storage frame, based on the identified layer; and   a frame decoder to decode the decoding target frame by referring to the selected reference frame.   
   
   
       22 . The apparatus of  claim 21 , wherein the reference frame selector selects, as the reference frame, a frame that is decoded and is stored prior to the decoding target frame, among storage frames included in the same layer as the decoding target frame or storage frames included in a lower layer of the decoding target frame.